1. Field of the Invention
The present invention is directed to optical lenses, and more particularly to optical lenses, such as wearable lenses, including contact lenses, implantable lenses, including intraocular lenses (IOLs) and any other type of device comprising an optical component that incorporates electronic circuits and associated antennas/antenna assemblies for information reception, information transmission and/or charging/energy harvesting.
2. Discussion of the Related Art
As electronic devices continue to be miniaturized, it is becoming increasingly more likely to create wearable or embeddable microelectronic devices for a variety of uses. Such uses may include monitoring aspects of body chemistry, administering controlled dosages of medications or therapeutic agents via various mechanisms, including automatically, in response to measurements, or in response to external control signals, and augmenting the performance of organs or tissues. Examples of such devices include glucose infusion pumps, pacemakers, defibrillators, ventricular assist devices and neurostimulators. A new, particularly useful field of application is in ophthalmic wearable lenses and contact lenses. For example, a wearable lens may incorporate a lens assembly having an electronically adjustable focus to augment or enhance performance of the eye. In another example, either with or without adjustable focus, a wearable contact lens may incorporate electronic sensors to detect concentrations of particular chemicals in the precorneal (tear) film. The use of embedded electronics in a lens assembly introduces a potential requirement for communication with the electronics and for a method of powering and/or re-energizing the electronics.
Often it is desirable to provide for communication to or from the embedded electronics for the purpose of control and/or data gathering. Communication of this nature should preferably be performed without direct physical connection to the lens electronics, such that the electronics may be fully sealed and to facilitate communication while the lens is in use. Hence it is desirable to couple signals to the lens electronics wirelessly using electromagnetic waves. Accordingly, there exists a need for an antenna structure appropriate for use in an optical lens assembly such as a contact lens.
The electronics in these applications often may require a power source. Accordingly, it may be desirable to incorporate a self-contained power storage device such as a rechargeable battery or capacitor. Alternately, the electronics may be inductively powered from a distance rather than being powered from a self-contained power storage device, and thus there is no need for recharging. An acceptable method for recharging a battery is through inductive coupling, whereby an external coil is magnetically coupled to a coil that is coupled to, connected to or otherwise associated with a charging circuit adapted to recharge the battery imbedded in the device. Accordingly, there exists a need for inductive structures, for example, antennas, antenna assemblies and/or coils appropriate for use in an optical lens assembly. Further, it is desirable to provide a convenient method for aligning the coil structure with an external inductive coil structure for efficient near-field coupling.
Embedding electronics and communication capability in a contact lens presents general challenges in a number of areas, including the limited size of the components, in particular the thickness as well as the maximum length and width, the limited energy storage capacity in batteries or super capacitators, the limited peak current consumption due to higher battery internal resistance in small batteries and limited charge storage in small capacitors, the limited average power consumption due to limited energy storage and the limited robustness and manufacturability of small and especially thin components. With respect to communication devices, specific challenges include limited antenna efficiency, which is directly related to size or area and for a loop antenna, the number of turns, and antenna efficiency. In addition, there is also a limited set of frequency bands allocated by regulatory bodies for these applications, the choice of which affects the efficiency of a given structure, the maximum allowable transmitter power, potential interference, and other aspects of the communication link. Further characteristics of on-body propagation and absorption depend on frequency, along with accepted safe limits for absorption of electromagnetic energy. Various government agencies may or may not issue guidelines or regulations relating thereto. Antenna efficiency on-body is degraded for predominantly electric-field or “E-field” antennas. Similarly, for wireless charging of the battery or similar device, the size of the antenna relates to the maximum inductance achievable and the maximum voltage or current that may be transferred to the device.
Accordingly, there exists a need for providing a mechanically robust antenna assembly that meets the requirements for functionality and performance in the volume and area of a contact lens.